A survey by investigators from University of North Carolina, Chapel Hill showed an increased risk of cancer, including leukemia, for people living near Three Mile Island (TMI), following the nuclear accident at the Pennsylvania facility on March 28, 1979.

Their study, published in Environmental Health Perspectives, challenged a 1990 Columbia University study that concluded radiation exposures were too low to cause a cancer increase. The new study says, "Cancer incidence, specifically lung cancer and leukemia, increased more following the TMI accident in areas estimated to have been in the pathway of radioactive plumes than in others areas."

According to the University of North Carolina study, the results provided evidence that people exposed to the most radiation were more than seven times more likely to get leukemia than those least exposed to radiation.

The study examined a population of 160,000 people living within 10 miles of TMI. Cancer incidence was reviewed at 25 local hospitals, from 1975 to 1985. At time of diagnosis, cancer cases were assigned to one of 69 areas in a geographical grid of TMI. The analysis concluded that cancer incidence was associated with accident doses: people exposed to the highest level of radioactivity faced the highest risk of developing cancer.

In the 1990 study, epidemiologists also found increased cancer risks. They concluded these were too small to be statistically significant, and not likely to be associated with the nuclear accident.

Dr. Steven B. Wing, author of the current study, calls for more surveillance of cancer and other possible health effects related to the TMI accident. "The potentially long lag between radiation exposure and cancer diagnosis suggests that studies of cancer incidence in the area should be continued past 1985," he writes. The previous authors of the Columbia study have not suggested that further study is necessary.